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Posted on Sun, May 29, 2011 : 1:55 p.m.

4 ways to make a natural and nontoxic mosquito repellent

By Linda Diane Feldt

Catnip (Nepeta spp) is attractive to most cats, but also acts as a natural repellent to mosquitoes. We’ve known for many years that oil made from catnip, called nepetalactone, in well-known research conducted about 10 years ago by Iowa State University, is more effective than DEET for short term exposure.

In a New England Journal of Medicine study from around the same time, catnip was not included as one of the natural botanical choices studied. But the study's observation of the limits of natural repellents agrees with my experience. Products containing DEET last far longer, while natural remedies need to be reapplied as often as every 20 to 30 minutes to remain effective.

I’ve been making, using and sharing catnip-based repellents for about 30 years, and appreciate that I can make it myself rather easily and very cheaply. It's also safer and nontoxic (I use the oil on my dog).

Reports from friends who have traveled to heavily mosquito-infested areas are very positive. It works, but has to be reapplied frequently. I used to include citronella and eucalyptus in my sprays, but now use catnip and yarrow flowers (see the end of the article) exclusively.

Here's how you can make your own natural mosquito repellent.

Method one:In a pinch, you can take sprig of catnip and crush them in your hands, releasing the oils and a strong scent. Tuck the plant into a hat, around the neckline of your clothes, and other places that are exposed. You can also rub the plant directly onto your skin, but that loses effectiveness rather quickly and leaves green stains.

Method two:Still quick, and a bit more effective, would be to make an oil-based infusion of the plant. The fastest way to do this is using your oven.

Gather the catnip leaves and stems and chop them finely to expose more surface area of the plant. Cover the bottom of a casserole dish with the plant. Cover the greens with oil. I use olive oil for its stability, though soy oil may also be a good choice as it may have some mild repellent ability on its own. I have not verified this claim.

Heat in a very slow oven (about 200 degrees) for 2 to 3 hours. I usually make this in the evening, and just turn off the oven for the night and let the mixture sit overnight in the oven.

When it is cool, strain out the leaves, and refrigerate the oil until you use it. The down side to this method is a house that smells strongly of catnip. It can be a bit much for people sensitive to smells. I wouldn’t recommend it if you have cats.

Catnip is easy to find around gardens, in fields, and against foundations. It is easy to find in Michigan. If you have doubts about confusing it with another mint, test it with a cat.

Linda Diane Feldt | Contributor

Method three:The longer method of making an oil is to fill a very clean jar with the chopped greens that have been only slightly compacted. Fill the jar with olive oil and cap with a lid. Shake to bring air bubbles to the top, and fill completely with the oil. Let that sit for two to six weeks. If you shake the jar every day, it will be ready in a shorter time. If you just let it sit in a cool dark place, give it six weeks to infuse.

Method four:I don’t care much for applying oil on a hot summer day, so an alcohol-based infusion is my preferred medium. The recipe is similar to the oil: Gather the leaves and stems of the plant, chop and fill a jar with the greens. Use 100-proof vodka to fill the jar. Screw a lid on tightly and set aside for two to six weeks. Like the oil, if you shake the jar every day it will infuse more quickly; otherwise wait six weeks.

After straining the alcohol from the plant, I fill a small spritzer bottle just halfway with the liquid, which is now called a tincture. I use water for the other half. This diluted liquid has a cooling effect when sprayed.

You will need to reapply the catnip repellent, whichever form you choose, about every 30 minutes to maintain optimal effectiveness.

The science behind using catnip remains a bit sketchy. Since catnip is an easy to grow weed (I’ve been removing it form my garden for over 25 years and still have more than I could ever use), there is no clear profit in the research.

In the journal article, the researchers endorse DEET products primarily because of their longer effectiveness. (See: Vol. 347, No. 1, July 4, 2002: "Comparative Efficacy of Insect Repellents Against Mosquito Bites.") That agrees with my observations, but I’d rather reapply frequently rather than use DEET.

With such a wet spring, it promises to be a summer with plenty of mosquitoes. If you’d like a cheap, effective and safer method of keeping them at bay, you might want to give catnip a try.

In a few weeks, yarrow (Achillea millefolium) flowers will also be available. Yarrow seems to work almost as well as catnip, and can be prepared in the same four ways outlined above. The wild white flowered yarrow is considered to be the most potent.

Linda Diane Feldt is a local Holistic Health Practitioner, author, and teacher. You can follow her on Twitter, visit her website, or contact her directly ldfeldt@holisticwisdom.org. The next weed walk is scheduled for Thursday, June 16 from 5:30-7:30 p.m. There is a small charge for this class. Contact Linda Diane directly to register.

Comments

Joe Chemler, Ph.D.

Mon, Jun 6, 2011 : 2:24 a.m.

Hi Linda,
It should be pointed out that the catnip study by Dr. Coats at the Iowa State University was never published. Rather, it was work that was presented at a ACS conference. If you unfamiliar with what conferences are, they are places where preliminary studies can be presented to the broader academic world. That means their work was never subject to the peer-review process.
In fact, Dr. Coats (although he referenced he was further studying catnip in a later study) never published his results. You should make clear the level of evidence you are presenting to your audience.

FredMax

Mon, May 30, 2011 : 1:03 p.m.

Interesting article, maybe some entrepeneur can commercialize this into a spray form with increased longevity.
I did try a non-toxic bee spray once; the targeted hornet's nest survived an entire can; but on the positive side, the entire neighborhood enjoyed a pleasant mint/anise/basil smell that lasted for many many days. Finally I just I killed em with a bit of boric acid.
My biggest mosquito lesson after living in a number of different rural homes is to design your deck/patio/outdoor-living-area into a very dry, open space. Mosquitos seem to congregate around protective objects like trees and shrubbery, as well as calm, moist areas. It takes some thought to build a pleasing landscape without large foilage, but it is possible.

DonBee

Mon, May 30, 2011 : 12:22 p.m.

I have citronella plants on the deck. When we go outside, A leaf in the pocket or tucked in the back of the hat works pretty good at keeping the bugs away.
Because of the wet spring we started a couple dozen extra plants, it is easy, cut a stem about 4 inches from the end, pull (not cut) all the large leaves off the stem, leaving only the last smaller leaf and push it in rich moist soil, 90 percent will turn into plants.

bedrog

Sun, May 29, 2011 : 10:34 p.m.

But how do you keep from getting attacked by cats looking to get stoned??

RunsWithScissors

Sun, May 29, 2011 : 10:19 p.m.

The common name for most Nepeta spp is catmint. True catnip is specifically Nepeta Cataria. Does your repellent require catmint or catnip? In other words, does catmint contain nepetalactone and does it contain it in the same amount as catnip?
thanks

Vivienne Armentrout

Sun, May 29, 2011 : 5:32 p.m.

I think there was a typo - you mean Achillea millifolium (scientific name for yarrow), right?
Is there any danger of staining for clothes or skin with any of these preparations?

Kelly Davenport

Sun, May 29, 2011 : 6:45 p.m.

The typo has been fixed, thank you!

glenn thompson

Sun, May 29, 2011 : 4:13 p.m.

I bet the catnip vodka would be quite tastey too.
I used to make iced catnip tea for my cat. He didn't like it all that well, preferring to just chew the fresh catnip, but I liked it.